CN112106312A - Multi-fiber interface automatic power reduction system and method - Google Patents

Abstract

An optical module (10) comprising a plurality of ports (12) configured to connect to a multi-fiber cable including transmit and receive fibers for the plurality of ports (12); a detector for each of the plurality of ports, the detector being configured to detect loss of signal at the port level; and a processor (24) configured to detect only the multifiber for which loss of signal is detected The affected ports of the cable perform automatic power reduction. The multi-fiber cable can be an MPO cable.

Description

Multi-fiber interface automatic power reduction system and method

technical field

The present disclosure generally relates to the field of optical networks. More particularly, the present disclosure relates to a multi-fiber interface automatic power reduction (APR) system and method based on spectrum-specific wavelength selective switch (WSS) response.

Background technique

Automatic Power Reduction (APR) is a term used in the context of laser safety. The system fiber typically has more power than the open interface can accept. Therefore, the system must detect an open connection and then reduce power for a certain period of time to limit exposure and potential eye damage. For example, this is specified by IEC60825.

Colorless Undirected (CD), Colorless Undirected Additive (CDA), and Colorless Undirected Undirected (CDC) Reconfigurable Optical Add-Drop Multiplexer (ROADM) architectures continue to gain popularity. These ROADM types typically utilize multi-fiber push-on (MPO) style cables or the like to maintain the manageability of the fibers within the node. Roughly speaking, these multi-fiber cables are considered a single point source from a laser safety point of view. Therefore, based on certain conditions, for example, the sum of the transmit powers of all sub-fibers cannot exceed the IEC 60825 class 1M ("1M") limit of approximately 21.3dBm. Therefore, if there are four active sub-fibers per cable, the maximum value per sub-fiber is about 15.3dBm.

In previous ROADM designs, this restriction could be respected without requiring any reaction mechanism. Targets for the number of channels, their spectral occupancy and system power spectral density (PSD) result in a total power below the required per sub-fiber maximum of 1M. In general, the PSD target of a channel remains the same regardless of its spectral occupancy. Therefore, the power requirement of the colorless channel Mux/Demux (CCMD) is not only related to the number of channels, but also to its spectral occupancy.

Combined with evolving technology, the drive to increase capacity results in a change that effectively increases the overall spectrum and correspondingly the power that a wavelength selective switch (WSS) must direct to a given CCMD (ie, each sub-fiber). An increase in baud rate (eg 56, 75, 90+GBaud) results in higher spectrum occupancy for these channels. In addition, the number of add/drop channels per CCMD is also increasing (eg, 12 to 24+). Also, the channel pre-combination acts as a port multiplier for the number of channels (eg, 4x24) per CCMD.

Together, these changes result in a given CCMD potentially including 96 channels, each with more than 90 GHz of spectrum. In practice, this is more than enough to fill in the C or L bands of many degrees. In this way it is no longer possible to stay below the 1M limit for cables that are not actively responding. A particular challenge is avoiding collateral damage to signals on other ports. Therefore, what is needed is a spectrally selective response to one or more corresponding APR triggers.

In the past, retention mechanisms or back-reflection-based APRs have often been used to maintain laser safety requirements. Due to the amount of spectrum, power is thus routed to a given CCMD port, it is no longer possible to keep the amplifier below eye-safe limits. Back-reflection-based APR is no longer available due to the angled physical contact (APC) termination of single-mode MPO cables.

SUMMARY OF THE INVENTION

In various exemplary embodiments, the present disclosure provides a spectrum/port specific APR system and method that relies on a corresponding loss of input signal (LOS) based WSS liquid crystal on silicon (LCoS) or similar Rapid changes in the grating pattern. Therefore, spectrum-specific WSS responses are utilized. It should be noted that LCoS is merely an exemplary technology here.

In one exemplary embodiment, the present disclosure provides an automatic power reduction (APR) system for an optical network module, the system comprising: a multi-fiber interface including a multi-fiber connection adapted to couple to one or more multi-fiber connections a plurality of ports of the device; a card processor operable to detect a loss of signal on an input port of the plurality of ports and compare the power of the associated output port to an activation threshold received by the card processor; and a module processor operable to trigger the optical network module to perform an APR procedure in the event that a loss of signal is detected on the input port and the power at the output port exceeds an activation threshold, and using wavelength selective switches coupled to the plurality of ports to attenuate the spectrum associated with the affected port. Optionally, the card processor and the module processor are respective functional parts of the same processor. The module processor is further operable to refuse to trigger the optical network module to perform an APR procedure if a loss of signal is detected on the input port but the power at the output port does not exceed the activation threshold, and use wavelength selective switches coupled to the plurality of ports to Attenuates the spectrum associated with the affected port. Triggering the optical network module to execute the APR procedure includes using hardware circuitry to cause the optical network module to execute the APR procedure with a priority over other procedures. Attenuating the spectrum associated with the affected port using the wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port by a predetermined amount received by the module processor. Alternatively, attenuating the spectrum associated with the affected port using wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port by a variable amount that depends on the power of the output port and The difference between the activation thresholds received by the module processor.

In another exemplary embodiment, the present disclosure provides an automatic power reduction (APR) method for an optical network module, the method comprising: given a multi-fiber interface, the multi-fiber interface includes a Multiple ports of more multi-fiber connectors, detecting loss of signal on the input ports of the multiple ports at the card processor, and comparing the power of the associated output port with the activation threshold received by the card processor. compare; and in the event that a loss of signal is detected on the input port and the power of the output port exceeds the activation threshold, triggering the optical network module at the module processor to execute the APR procedure and use wavelength selective switches coupled to the plurality of ports to attenuate and Spectrum associated with the affected port. Optionally, the card processor and the module processor are respective functional parts of the same processor. The method also includes, if a loss of signal is detected on the input port but the power at the output port does not exceed the activation threshold, refusing to trigger the optical network module to perform an APR procedure at the module processor and using wavelength selective switches coupled to the plurality of ports to attenuate the spectrum associated with the affected port. Triggering the optical network module to execute the APR procedure includes using hardware circuitry to cause the optical network module to execute the APR procedure with a priority over other procedures. Attenuating the spectrum associated with the affected port using the wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port by a predetermined amount received by the module processor. Alternatively, attenuating the spectrum associated with the affected port using wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port by a variable amount that depends on the power of the output port and The difference between the activation thresholds received by the module processor.

In another exemplary embodiment, the present disclosure provides a computer-readable medium storing computer-executable instructions, the computer-readable medium being configured to cause the following steps to occur: given a multi-fiber interface, the multi-fiber interface includes A plurality of ports adapted to be coupled to one or more multi-fiber connectors, detecting a loss of signal on an input port of the plurality of ports at the card processor, and correlating the power of the associated output port with the card processor The received activation thresholds are compared; and in the event that a loss of signal is detected on the input port and the power of the output port exceeds the activation threshold, triggering the optical network module at the module processor to perform an automatic power reduction (APR) procedure and use the coupling Wavelength selective switches to multiple ports to attenuate the spectrum associated with the affected ports. Optionally, the card processor and the module processor are respective functional parts of the same processor. The steps also include, in the event that a loss of signal is detected on the input port but the power of the output port does not exceed an activation threshold, refusing to trigger the optical network module to perform an APR procedure at the module processor and using wavelength selective switches coupled to the plurality of ports to attenuate the spectrum associated with the affected port. Triggering the optical network module to execute the APR procedure includes using hardware circuitry to cause the optical network module to execute the APR procedure with a priority over other procedures. Attenuating the spectrum associated with the affected port using the wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port by a predetermined amount received by the module processor. Alternatively, attenuating the spectrum associated with the affected port using wavelength selective switches coupled to the plurality of ports includes attenuating the spectrum associated with the affected port with a variable amount that depends on the power of the affected port Difference from the activation threshold received by the module processor.

Description of drawings

The present disclosure is illustrated and described herein with reference to the various drawings in which like reference numerals are used where appropriate to refer to like system components/method steps, and wherein:

1 is a schematic diagram illustrating an exemplary embodiment of an APR system of the present disclosure;

FIG. 2 is a flowchart illustrating an exemplary embodiment of the APR method of the present disclosure;

3 is a schematic diagram illustrating APR applied only to the spectrum of the affected port in accordance with the APR systems and methods of FIGS. 1 and 2;

4 is a schematic diagram illustrating the need for each sub-fiber APR response so that other ports are not affected; and

5 is a flow diagram illustrating an automatic power reduction (APR) process for an optical network module.

Detailed ways

Furthermore, in general, the present disclosure provides a spectrum/port specific APR system and method that relies on rapid changes in the WSS LCoS grating pattern based on the corresponding input LOS. Therefore, spectrum-specific WSS responses are utilized.

The challenge with multi-fiber interfaces, such as MPO ports, is that the collection of sub-fibers is considered a single-point (or near-single-point) source due to the small separation between the sub-fibers. In this way, a 1M safety limit is used for the sum of the light emissions of all sub-fibers. In C-band, the limit is about 21.3dBm, which equates to no more than about 15.3dBm per sub-fiber with four pairs of fibers per cable.

For example, in previous generations of CDC ROADMs, it was possible to keep the power of each sub-fiber below the maximum level while still achieving the proper PSD required for proper system performance. However, at 56Gbaud there are up to 16 channels. In recent CDC ROADM designs, it is no longer possible to achieve the desired PSD without exceeding the limit of about 15.3dBm per sub-fiber. This is due to the substantial increase in total signal spectrum associated with each CCMD's add/drop channel hop to 24, the increase in supported baud rates (ie, spectrum occupancy), and channel pre-combining.

Table 1 shows how staying below the 1M limit was possible as a set in the previous generation CDC (CCMD8x16@56GHz), but this is no longer possible. The latest CCMD designs are now capable of accommodating 96 channels at 90GHz or higher. This is enough to fill a spectrum of two degrees.

Table 1: Comparison of power requirements for each sub-fiber based on CCMD port and signal baud rate

The present disclosure takes advantage of the properties of bidirectional fiber pairs in multi-fiber cables. The transmit (demux) and receive (mux) fiber pairs for a given port are collocated in the same MPO cable. In this way, the input LOS can be used to detect open connections. Unlike duplex LC connectors, MPO cable sub-fibers cannot be subdivided, so input LOS represents a reliable detection mechanism. Since the standard for single-mode MPO cables is APC termination, this makes reflection-based detection impossible.

When a LOS is detected on an input port, the response is to reduce the power of the spectrum cross-connected to that port through the attenuation capability of the WSS module. Therefore, services on other ports are not affected. Additional logic compares the output power to an activation threshold before responding. The system can choose to skip the APR response if the power on that port has fallen below the multi-fiber maximum.

To meet class 1M timing requirements, hardware (HW) lines can be used to interrupt all other WSS module processes and prioritize one or more ports to power down as needed. The following diagram illustrates and describes how this mechanism is implemented.

Referring now specifically to FIG. 1, in one exemplary embodiment, the APR system 10 of the present disclosure includes an MPO interface 12, in this case having 4 Tx/Rx sub-fibers. The MPO interface 12 is coupled to Mux WSS 14 and DemuxWSS 16, both of which are coupled to amplifiers 18 (pre or post) and line amplifiers 22 within module 20, as is conventional. A card CPU or FPGA 24 is provided in the line amplifier 22, and a module CPU or FPGA is provided in the module 20, both operable to implement the functions of the present disclosure. When the card CPU or FPGA 24 detects a LOS on port 1 12(1), the output power of port 1 12(1) is compared to an activation threshold. If the activation threshold is exceeded, the HW line is activated to trigger the module 20 to prioritize incoming APR commands. In particular, the module 20 is notified via serial communication, and if desired, the HW line may be used based on timing requirements. These APR commands are sent to module 24 and indicate on which ports (eg, port 1 12(1)) the APR is to be applied. Module 24 then applies APR attenuation only to the spectrum cross-connected to the affected port (eg, port 1 12(1)). Other ports of MPO interface 12 (or other MPO interfaces) are not affected. Note that the power reduction slew rate can be controlled to mitigate transient effects. For example, the LOS here can be a pulled connector or fiber break, as the purpose is to ensure that free space emitted light is at a safe power level.

This method is shown in Figure 2. Method 30 begins with LOS detection 32 on port X. If no LOS is detected, the power or attenuation controller operates normally and no APR action 34 is taken. If LOS is detected, the power on port X is compared 36 to an activation threshold. If the power on port X has been less than the activation threshold, the power or attenuation controller is functioning normally and no APR action 38 is taken. If the power on port X exceeds the activation threshold, the WSS spectrum on port X will be attenuated by 40 as part of the APR action.

Figure 3 shows this attenuation on port 1 only. It can be seen that, in the example provided, the common input receives comparable WSS spectra in relation to the outputs of ports 1, 2 and 3 before and after APR. After APR, the WSS spectral output associated with port 1 is attenuated, while the WSS spectral output associated with ports 2 and 3 remains unchanged.

Figure 4 is a schematic diagram illustrating the need for each sub-fiber APR response so that other ports are not affected. Since the APR scheme only targets the WSS spectrum associated with the selected port 50, numerous other ports and channels are not affected.

It should be recognized that, depending on the examples, certain acts or events of any of the techniques described herein can be performed in a different order, added, combined, or omitted entirely (eg, not all described acts or events are essential for implementation of the techniques). necessary). Furthermore, in some examples, actions or events may be performed concurrently, such as through multithreading, interrupt processing, or multiple processors, rather than sequentially.

In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to tangible media such as data storage media, or communication media, including any medium that facilitates transfer of a computer program from one place to another, eg, according to a communication protocol. In this manner, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium or (2) a communication medium such as a signal or carrier wave. Data storage media can be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementing the techniques described in this disclosure. The computer program product may comprise a computer readable medium.

By way of example only, and not limitation, such computer-readable storage media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other Other media in the form of data structures that store the required program code and that can be accessed by the computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are sent from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, coaxial cable, fiber optic cable, Twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are all included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and blu-ray disc, where discs typically reproduce data magnetically, while discs reproduce optically using lasers data. Combinations of the above should also be included within the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), complex programmable Logic Devices (CPLDs) or other equivalent integrated or discrete logic circuits. Accordingly, the term "processor," as used herein may refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein may be provided in dedicated hardware and/or software modules. Furthermore, these techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in various devices or apparatuses including integrated circuits (ICs) or groups of ICs (eg, chip sets). Various components, modules or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, the various elements may be combined in hardware elements, or provided by a collection of interoperable hardware elements, including one or more processors as described above, together with appropriate software and/or firmware .

Thus, the present disclosure addresses laser safety challenges without resorting to additional HMs or methods that increase cost and degrade performance. Alternatives to using WSS to reduce power are: mute the amps, which will unnecessarily affect all traffic associated with that dimension (causing collateral damage), or add shutters on all WSS demux ports ), which would add thousands of cost and increase ROADM losses, thus impacting performance. Therefore, the present disclosure provides a better solution. Advantageously, the systems and methods provided herein are flexible with respect to the number of active sub-fibers. Provides the response of each sub-fiber, which uses the input LOS to trigger the APR to the level calculated by each sub-fiber based on the maximum power limit, e.g., <15dBm, based on the specific implementation of the four sub-fibers per MOP , and given assumptions about photodiode accuracy, etc.

Possible attenuation schemes include fixed attenuation, port-specific fixed attenuation, and just enough attenuation. In fixed attenuation, if an input LOS is detected, the spectral attenuation associated with the corresponding port defaults to a common (settable) value, eg about 5dB, regardless of port power. This is simple and responsive, but can cause unwanted high-power transients. In the port-specific fixed attenuation, the minimum nominal power value of each port can be considered. Again, this is simple and responsive, but can still cause unwanted high-power transients. In just enough decay, one needs to consider how much higher the output is than the APR activation power, and add a lot of offset to achieve eye-safe levels. This minimizes power transients, but requires more computational complexity. This can be mitigated, for example, by preparing attenuation curves for each port.

5 is a flow diagram of an automatic power reduction (APR) process 80 for an optical network module. Process 80 includes, in a multi-fiber interface including one or more ports adapted to couple to one or more multi-fiber connectors, detecting at the card processor for an input port of the one or more ports. loss of signal and comparing the power of the associated output port to the activation threshold received by the card processor (step 82); and, in the event that a loss of signal is detected on the input port and the power of the output port exceeds the activation threshold , the optical network module is triggered at the module processor to execute the APR procedure and attenuate the spectrum associated with the affected port using wavelength selective switches coupled to one or more ports (step 84). Card processors and modular processors can be separate functional parts of the same processor.

Process 80 can further include, in the event that a loss of signal is detected on the input port but the power of the output port does not exceed the activation threshold, refusing to trigger the optical network module at the module processor to execute the APR procedure, and using coupling to one or more Port wavelength selective switch to attenuate the spectrum associated with the affected port. Triggering the optical network module to execute the APR procedure can include using the communication line to cause the optical network module to execute the APR procedure with priority over other procedures. Attenuating the spectrum associated with the affected port using the wavelength selective switch coupled to the one or more ports can include attenuating the spectrum associated with the affected port by a predetermined amount received by the module processor. Attenuating the spectrum associated with the affected port using a wavelength selective switch coupled to one or more ports can include attenuating the spectrum associated with the affected port by a variable amount that depends on the power of the affected port Difference from the activation threshold received by the module processor.

Although the present disclosure has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve similar results . All such equivalent embodiments and examples are within the spirit and scope of this disclosure and are therefore contemplated, and are intended to be covered for all purposes by the following non-limiting claims.

Claims (15)

1. An optical module (10), comprising: a plurality of ports (12) configured to connect to a multi-fiber cable including transmit and receive fibers for the plurality of ports (12); a detector for each of the plurality of ports, the detector configured to detect loss of signal at the port level; and A processor (24) configured to perform automatic power reduction only on the affected ports (12) of the multi-fiber cable where loss of signal is detected. 2. The optical network module of claim 1, wherein the multi-fiber cable is an MPO cable. 3. The optical network module (10) of any of claims 1 to 2, wherein the detected loss of signal is based on a comparison of the power detected by the detector to a threshold. 4. The optical network module (10) according to any one of claims 1 to 3, wherein the optical module (10) is one of an interconnection module, a dimension module, and a multiplexer and demultiplexer module anyone. 5. The optical network module (10) of any one of claims 1 to 4, wherein the sum of the optical powers on all fibers in the multi-fiber cable exceeds about 21.3 dBm. 6. The optical network module (10) according to any one of claims 1 to 5, wherein the automatic power reduction is an attenuation of the frequency spectrum of the affected port caused by a wavelength selective switch (20). 7. The optical network module (10) of claim 6, wherein the automatic power reduction is prioritized by a hardware line connected to the wavelength selective switch (20). 8. A method comprising: receiving a plurality of ports (12) from a multi-fiber cable including transmit and receive fibers for the plurality of ports (12); The plurality of ports (12) are monitored by a plurality of detectors to detect loss of signal at the port level; and Automatic power reduction is performed only on the affected ports of the multi-fiber cable where signal loss is detected. 9. The method of claim 8, wherein the multi-fiber cable is an MPO cable. 10. The method of any of claims 8 to 9, wherein the detected loss of signal is based on a comparison of the power detected by the detector to a threshold. 11. The method according to any one of claims 8 to 10, wherein the method is performed in an optical module (10) which is an interconnection module, a dimension module and a multiplexer and demultiplexer any of the controller modules. 12. The method of any one of claims 8 to 11, wherein the sum of the optical powers on all fibers in the multi-fiber cable exceeds about 21.3 dBm. 13. The method according to any one of claims 8 to 12, wherein the automatic power reduction is an attenuation of the spectrum of the affected port by a wavelength selective switch (20). 14. The method of claim 13, wherein the automatic power reduction is prioritized by a hardware line connected to the wavelength selective switch (20). 15. A non-transitory computer readable medium storing computer executable instructions configured to cause a processor to perform the method of any of claims 8 to 14.

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